THE STEREOSPECIFIC POLYMERIZATION OF DIENES: MECHANISTIC ASPECTS

Abstract The factors that determine microstructure and stereospecificity in polymerization of 1, 3-dienes with transition metal catalysts are examined in the light of the most recent results. The use of 1, 4-disubstituted butadienes has clarified that monomer insertion occurs via a cis-addition and which prochiral face the monomer presents to the catalyst. A dependence of stereospecificity on the monomer has been observed with some catalysts, an indication that stereospecificity does not depend only on the steric structure of the catalytic complex. The formation of 1, 2 stereoregular polymers is discussed. It is shown that with some common catalysts 1, 2 butadiene units derive from a coordination of the monomer as a bidentate ligand.